An air bag module is part of an inflatable restraint system that is employed in an automobile for protecting an occupant against injury by physically restraining the occupant's body when the automobile encounters a collision. A side impact air bag module protects occupants from side collisions to the automobile and can be positioned in a seat, on the exterior of a seat, in a door or in a side pillar. A side impact air bag module typically includes an air bag cushion and an inflator contained within a reaction canister. The inflator has an elongated cylindrical housing having gas exhaust ports and containing gas generant that, once triggered by a remote collision sensor, provides the inflation gas for inflating the air bag cushion. A hybrid inflator has gas exhaust ports located centrally or at one end while pyrotechnic inflators have gas exhaust ports distributed substantially along their entire length.
In the event of an impact, the inflator is actuated, and the air bag is inflated into a position between the vehicle occupant in the vehicle seat and the adjacent side structure of the vehicle. The air bag protects the vehicle occupant from forcibly being struck by parts of the side structure of the vehicle. The air bag can also help protect the vehicle occupant from objects which might intrude into the vehicle, such as a pole or a tree, during the side impact.
There is a need to reduce the size of an air bag module, the number of parts of an air bag module assembly and the overall manufacturing costs of an air bag module assembly.
Recently, it has been proposed to employ an air bag module with a clamshell-type cover for housing an air bag inflator and an inflatable air bag. Such a cover arrangement requires fewer parts, less assembly time, is conducive to the automated assembly and helps reduce the complexity and size of an air bag module.
One such air bag module is disclosed in U.S. Pat. No. 5,645,295 to White, Jr. et al. The air bag module includes an air bag, an inflator assembly and a cover. The cover includes first and second cover parts which are releasably interconnected by a rupturable portion of the cover. The cover has a closed condition in which the first and second cover parts enclose the air bag when the air bag is in a deflated condition. The rupturable portion of the cover forms a first hinge about which the cover parts are pivotable relative to each other into the closed condition, during assembly thereof. A second hinge is formed where the inflator assembly is mounted in the cover. When the air bag inflates, the rupturable portion of the cover is ruptured and the first and second cover parts pivot about the second hinge to enable the air bag to inflate out of the cover.
In the air bag module of said U.S. Pat. No. 5,645,295, the clamshell-type cover utilizes a rupturable hinge portion which ruptures when the air bag inflates. Although the clamshell cover of U.S. Pat. No. 5,645,295 provides the benefits of a less complex and reduced size air bag module, the cover arrangement requires that inflator is assembled directly opposite the rupturable hinge. Such an arrangement limits the possibility of arranging the inflator assembly in other orientations than opposite that of the rupturable hinge. Moreover, such an arrangement limits the ability to design the first and second cover parts to enable the air bag to inflate from the cover at any desired location, particularly with respect to the inflator assembly.